In a conventional seat belt apparatus, there is known a construction in which a remainder switch for outputting an ON/OFF signal for detecting a wearing or non-wearing state of a seat belt is disposed inside of a seat belt retractor mounted in a vehicle. A wearing state of the seat belt occurs when the seat belt is worn by an occupant of the vehicle so as to securely position and restrain the occupant within a seat of the vehicle.
In the seat belt apparatus, three gears, which are linked with the rotation of a spindle, are provided, and projecting portions which are formed on sides of the gears are brought into abutment with each other, to thereby drive a switch lever which is adapted to switch on or off the reminder switch.
In the conventional seat belt apparatus, a projecting portion on the gear, disposed at a middle of the three gears, is brought into abutment with a projecting portion on one of the remaining gears so as to shift the switch when the belt is pulled out, while the projecting portion is brought into abutment with a projecting portion on the other gear to shift the switch when the belt is retracted. Therefore, a deviation in the shifting position of the switch may be produced between when the belt is pulled out and when the belt is retracted. Thus, it may be required that the reminder switch is shifted properly even in a maximum retracting position when the occupant is restrained.
On the other hand, the two projecting portions may be provided on the gear disposed in middle the positions where the projecting portions are proximate the projecting portions of the remaining two gears in the shift positions. In this case, however, there may be a possibility that the projecting portions interfere with each other unintentionally at a certain number of revolutions.